ArbNotes

November 8, 2013

By Maddy Reynolds

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If you’ve been for a walk in the Lower Arb during the past year, you’ll have noticed various barren-looking regions that were covered by conifer plantations, until recently. One such area that you may not have thoroughly explored is the northeast corner of the Arb, near the Canada Avenue entrance. The recent Arb management activity of pine removal in this region allows us to observe successional changes close up. One of the most striking features of this succession is the emergence of aspen.

Aspen trees are an early successional species that establish themselves quickly in areas that have recently experienced a disturbance. They have a high reproductive rate because they are able to propagate, not only through the distribution of seeds, but also through suckering. Aspen grow in clonal colonies, meaning that a vast stand of trees may contain only a few genetically distinct individuals. These individuals extend themselves by sending out root suckers with the capability of creating new trees up to 98 to 131 feet away from the original parent organism. Often, suckering occurs more rapidly after the destruction of the aboveground biomass of the tree, so disturbance actually triggers production.

As an early successional species, aspen is fairly short-lived, usually surviving only about 20 years before giving way to later successional species, such as pine, spruce, and fir, or hardwood species like oak and walnut. It is generally found in higher-elevation soils, but has adapted to many types of habitats, making it the most wide-ranging tree species in North America.

Here in the Arb, we don’t intend for coniferous species to succeed the emerging aspen; rather, we plan to seed deciduous hardwood species beginning in 2014-2015. Still, we encourage you to come out to see the aspen and to witness the changes occurring in the land as it passes through the early stages of succession.